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Chemistry Chapter 3 Notes
Section 3.1: Properties of Matter
Section 3.1: Properties of Matter
1) Matter is anything that has mass and takes
up space. If the matter has a uniform
composition, then it is called a substance.
Uniform
Not Uniform
Section 3.1: Properties of Matter
1) Matter is anything that has mass and takes
up space. If the matter has a uniform
composition, then it is called a substance,
or pure substance. [This includes all
elements, like iron, carbon, and oxygen,
and compounds of the elements, like salt,
water, and acetic acid.]
[Explain why salt and water are both
substances, but seawater (salty water) is not.]
2) Matter is identified by it’s properties physical and chemical.
a) Physical properties - can be observed or
measured without changing the sample’s
composition [(chemicals that make it up).
(For example, if you rip a piece of paper,
you’ve changed the size, but it’s still
paper.)]
Two classifications of physical properties extensive and intensive.
i. Extensive physical properties depend on
how much of the sample you have, like
mass and volume.
i. Extensive physical properties depend on
how much of the sample you have, like
mass and volume.
ii. Intensive physical properties do not
depend on how much of the sample you
have, they will still be the same, like
density. [the density of a piece of copper
is 8.92 g/cm3 whether you have a little
piece or if you have a truckload.]
b) Chemical properties describe the sample’s
ability to combine with or change into
other substances. [If iron (an element - a
substance) combines with oxygen (an
element - a substance) it will form iron
oxide (a compound - a substance), which
we usually call rust.]
*Try to classify each of the following
properties as a physical or chemical property.
*If it is a physical property, also state if it is
extensive or intensive.
Size
Density
Color
Flammable
•Corrosive
•Phase of Matter
3) [There are five phases of matter (also
called states of matter.) Each phase has
specific physical properties associated
with it. Solid, liquids, and gases are by far
the most common on earth, but plasmas
(extremely high electrical energy - like
lightening bolts) are the most common in
the universe as all stars are made up of
plasma. The fifth phase does not occur
naturally anywhere in the universe and is
still undergoing laboratory research.]
a) [Solids have a definite shape and a definite
volume. The atoms in a solid are usually
packed very close together and are often
locked into a geometric shape (crystal).
The atoms can only vibrate a little.]
b) [Liquids do not have a definite shape, but
they still have a definite volume. The
atoms in a liquid are still close together,
but are free to slide around each other making them a fluid (able to flow). ]
c) [Gases do not have a definite shape or a
definite volume. The atoms spread apart
as much as possible and move very fast.]
d) Plasmas are similar to gases, electrons get
ripped loose of atoms.
Section 3.2: Changes in Matter
Section 3.2: Changes in Matter
1) two types of changes - physical and
chemical.
a) Physical changes alter a substance without
changing its composition. [Common
physical changes involve change in shape
and size - in other words, changes to a
physical property. ]
i. Phase changes are ALWAYS physical
changes. [The composition of the
substance does not change, just how close
the atoms are to each other and how much
they can move. This includes melting,
freezing, evaporation, vaporizing
(boiling), and condensing. ]
b) Chemical changes alter the composition of
a substance. [Thus chemical changes
always alter physical properties. ]
b) Chemical changes alter the composition of
a substance. Thus chemical changes
always alter physical properties.
i. [Evidences of chemical changes include
changes in color, texture, odor, the
appearance or disappearance of a solid,
and possibly a change in magnetic ability.]
[Note: it can be very tricky to tell physical
and chemical changes apart just by the
appearance. For instance, if you paint a
piece of paper orange, it is a physical change,
but if iron turns to orange rust, it is a
chemical change. ]
[You cannot even think that physical changes
can be easily reversed and chemical changes
cannot, for it would be hard to “unpaint” the
orange paper, but the orange rust can be
turned back into iron by rubbing it with
aluminum foil.]
[With each change, you must ask yourself if
you’ve changed the chemical composition of
the original substance or not. If you did, then
it is a chemical change. If you did not, then
it is a physical change. ]
2) The Law of Conservation of Matter
applies to physical and chemical changes.
The mass of the parts will be the same in
the beginning and in the end. [ If you rip a
piece of paper into 4 parts, the mass of all
4 parts must equal the mass of the original
piece of paper. Also, the mass of all
substances before a chemical change must
equal the mass of all new substances after
the chemical change.]
*When burning a log in a fireplace, you start
with a large piece of wood and get just a little
bit of ashes left over. If the law of
conservation of mass is true (and it is), what
happened to the rest of the mass?
Section 3.3: Mixtures of Matter
Section 3.3: Mixtures of Matter
1) A mixture
is a combination of two or more
substances in which each retains their
individual chemical properties. [Mixtures
can be separated into the substances that
make them up by physical means.]
There are two types of mixtures heterogeneous and homogeneous.
a) Heterogeneous mixtures
have an uneven spreading of the
substances, and the distinct parts of the
mixture are often easily distinguished.
There are two types of heterogeneous
mixtures - suspensions and colloids.
[remember paraphrasing!
example
Heterogeneous – uneven distribution
two types
suspensions & colloids]
i. Suspensions
heterogeneous mixtures in which the
different parts can settle upon standing.
Anything that tells you to shake well
before using is a suspension, like
orange juice with pulp and italian salad
dressing.
II. Colloids
are heterogeneous mixtures in which the
different parts do not settle, like smoke
and fog. Colloids will scatter light, a
property called the Tyndall Effect.
 Tyndall Effect
b) Homogeneous mixtures
have an even spreading of the substances,
[making the parts of the mixture somewhat
difficult to distinguish, which is the idea
behind “homogenizing” milk - making it the
same from the first glass to the last.]
Homogeneous mixtures are often also called
solutions. The two parts of a solution are
the solute (thing being dissolved, or in lesser
amounts) and the solvent (thing doing the
dissolving, or in greater amount).
2) Mixtures must be separable by physical
means. [ This could be simple, like using a
magnet to pull iron out of sand, or using
your fingers to pull marshmallows out of
Lucky Charms Cereal, but often mixtures
are harder than that to separate.
Depending on the actual mixture,]
chemists often use one of four basic ways
to separate mixtures - filtration,
distillation, crystallization, and
chromatography.
a) Filtration
uses a filter to remove large, undissolved
particles from a heterogeneous mixture.
[The particles get trapped by the filter as
the rest of the mixture travels through the
filter. ]
b) Distillation
uses the different boiling temperatures
of the liquid parts of a homogeneous
mixture to separate the parts. [The part
with the lowest boiling point will vaporize
(boil out) first, and if desired can be
collected and condensed back into a liquid.
This process can be repeated until only
one part of the original mixture is left.
][they do this to liquor to make it
stronger!]
c) Crystallization
removes the liquid part(s) of a
homogeneous mixture to leave the solid
part(s) behind. The liquid is removed by
evaporation, or if time is an issue,
vaporization.
d) Chromatography
separates a homogenous mixture based
on how far it can travel through a certain
area. There are many, many types of
chromatography that can do everything
from separate dyes in an ink pen to
separate the parts of DNA.
Section 3.4: Elements and Compounds
Section 3.4: Elements and Compounds
1) Pure substances can be classified into two
groups - elements and compounds.
a) Elements
contain atoms that are all the same, and
cannot be broken down by physical or
chemical means (it takes nuclear means).
There are 91 naturally occurring elements,
and several more that have been made by
scientists. The best way to check if a
substance is an element is to find it on the
Periodic Table of the Elements.
b) Compounds
contain atoms of two or more elements
arranged in a specific ratio that is always the
same. Unlike mixtures, compounds cannot
be separated by physical means; separation
can only be done chemically. [When a
compound is formed, its properties are
usually nothing like the properties of the
atoms that make it up. Because the atoms of
a compound must always be of the same
whole number ratio, many different rules can
be established. ]
i. The law of definite proportions
says that no matter how much of the
compound you have, the ratio of the
masses of the elements is always the same.
[This means the percent by mass of each
element in a compound can be calculated.
For example, if we have 18 g of water, 16
g comes from oxygen, and 2 g comes from
hydrogen. Thus water is 89% oxygen by
mass and 11% hydrogen by mass. ]
ii. The law of multiple proportions
says that elements can combine in
different whole number ratios to make
different compounds. [ For example, water
has a ratio of 1 oxygen atom to 2
hydrogen atoms, while peroxide has a
ratio of 2 oxygen atoms to 2 hydrogen
atoms. ]
Matter
Mixtures
Heterogeneous
Colloids
Substances
Homogeneous
Elements
Suspensions
Solutions
Compounds